Help! Don't want to blow myself up. Lightswitch woes.

[boogaloo]

Hello. Wonder if anyone can help. I've just removed a lightswitch that wasn't working and got thoroughly confused. I was removing a dimmer switch (silver one, attached) and was surprised to see 3 sets of wires (i.e.. 3x red, 3x black etc). The black wires all seem to be joined and capped off in a plastic connector. The red wires had 2 red wires going into one switch input, and one going into the other.

What's going on?? Yes - I know that tape's not proper insulating tape. I just put it on for a very temporary measure while I sort this out today.

I'm trying to attach a simple 1 way switch, which just has an L1 and a COMM input.



Any advice appreciated!

 

[boogaloo]

By the way, all the wires originally come from three grey-shielded wires, where each wire has (as I'd expect) one black one red and one earth, so the wires aren't incorrectly sheathed.

 

[swampy2]

Its been wired as loop in through switch, 3 blacks are neutrals correctly terminated in a connector block, 2 reds are live in & live out(connect to com), single red is switch wire to light(connect to L1).

3 x twin & earths = 1 live,neutral,earth (IN)
1 live,neutral,earth (OUT)
1 switched live,neutral,earth to light

 

[rjm2k]

See the wiki "looping at switches"

//www.diynot.com/wiki/Electrics:Lighting-Circuit-layouts

Your 3 blacks in the connector block are 1 neutral in and 1 neutral out plus 1 neutral to the lamp.

The single red from L2 is the switched live and goes to L1 on your new switch and is paired with the neutral to the lamp mentioned above.

The 2 joined reds are your live in and live out, these go to comm on your new switch.

Sounds like the previous switch was 2 way wired as 1 way so either L2 or L1 could have been used.

Job done.

 

[boogaloo]

Thanks so much folks. I added the new switch and now the light stays on irrespective of what position the switch is in!! Does that suggest that I've got one of the red wires paired up in the wrong place?

 

[rjm2k]

sure does and you will probably find that some of your other lights no longer work

 

[boogaloo]

You're right! They don't! Is there an risk with just trying different combinations?

 

[rjm2k]

not normally recommended but in this instance provided you leave the neutrals alone and only swap reds you should be ok, remembering to switch the power off of course!

 

[ekmdgrf]

sure does and you will probably find that some of your other lights no longer work

That's easily fixed. Flick the switch